Backend refactoring: KjcEngine has been split up into separate classes for preprocessing, compiling, and running.

app/PdePreprocessor.java

@@ -0,0 +1,11 @@
+// This class will be the new CUP-generated preprocessor.
+//
+public class PdePreprocessor {
+
+    public PdePreprocessor() {
+    }
+
+    public String writeJava(String name, boolean kjc) {
+	return "This class is currently purely abstract";
+    }
+}